Causes of pulmonary granulomas: a retrospective study of 500 cases from seven countries.

BACKGROUND: The frequencies of various causes of pulmonary granulomas in pathological material are unknown, as is the influence of geographical location on aetiology. The aim of this study was to identify the causes of pulmonary granulomas in pathological specimens, to define their frequencies, and to determine whether these causes vary by geographical location. METHODS: 500 lung biopsies and resections containing granulomas were reviewed retrospectively by expert pulmonary pathologists from 10 institutions in seven countries. Fifty consecutive cases from each location were assigned a diagnosis based on histological features and available clinical/microbiological data. RESULTS: A specific cause was identified in 58% of cases (290/500), most commonly sarcoidosis (136, 27%) and mycobacterial or fungal infections (125, 25%). Mycobacteria were identified in 19% of cases outside the USA versus 8% within the USA. In contrast, fungi accounted for 19% cases in the USA versus 4% in other locations. Fungi were mostly detected by histology, whereas most mycobacteria were identified in cultures. In 42% of cases (210/500) an aetiology could not be determined. CONCLUSIONS: Across several geographical settings, sarcoidosis and infections are the most common causes of pulmonary granulomas diagnosed in pathological specimens. Fungi are more commonly identified than mycobacteria in the USA, whereas the reverse is true in other countries. A definite aetiology cannot be demonstrated in more than a third of all cases of pulmonary granulomas, even after histological examination. These findings highlight the need to submit material for histology as well as cultures in all cases in which granulomatous disease enters the differential diagnosis.

Benign and Malignant Mesothelial Proliferation.

Malignant mesothelioma (MM) is a rare primary malignant tumor of the surface serosal cells. The diagnosis of MM is challenging with a broad differential diagnosis. For many decades, studies have focused on distinguishing MM from other types of cancer; however, benign mesothelial cell hyperplasia, especially in small biopsies, has emerged as a major problem. The features of pleural lesions are somewhat different from peritoneal diseases, and this article primarily focuses on pleural diseases. Thorough interpretation and correlation of clinical, radiologic, and pathologic findings are essential for a correct diagnosis.

Pulmonary effects of deltamethrin inhalation: an experimental study in rats.

Deltamethrin is a synthetic pyrethroid widely used as the insecticide of choice especially for local vector mosquitoes in most countries. The application is mostly by cold aerosol spraying using vehicle-mounted equipment with a duration of 3-4 months during the summer. This experimental study aimed to evaluate the morphologic changes in the lungs caused by the inhalation of this insecticide. The study was performed on 30 mature male Wistar rats. While 10 of the rats were used as control group, 20 rats, separated into two groups, were exposed to 1:10 dilution of deltamethrin aerosol spray for 30 min each day for 45 days in doses of 6.0 and 12.0 mg/m3. The animals were sacrificed and tissue samples taken from the lungs were processed for both light microscopy and transmission electron microscopy. Light microscopic examination revealed heavy congestion, marked perivascular edema, and lymphoplasmocytic infiltration with focal nonspecific interstitial pneumonia, foamy macrophage accumulation, emphysema, peribronchial lymphoid tissue hyperplasia, and focal hemorrhage. Ultrastructurally, the ciliated cells of the airways appeared swollen with a few structurally abnormal cilia. Alveolar lining cells revealed mild degeneration and a slight hyperplasia in type II cells. Increases in the number of collagen bundles and edema in the alveolar septa were also noted.

Specificity of MOC-31 and HBME-1 immunohistochemistry in the differential diagnosis of adenocarcinoma and malignant mesothelioma: a study on environmental malignant mesothelioma cases from Turkish villages.

Histological diagnosis of malignant mesothelioma (MM) and differentiation from adenocarcinoma is often difficult. A number of clinical, radiologic, histologic and histochemical criteria have been used as diagnostic aids, but most cases cannot be readily classified on the basis of these characteristics. In recent years, a panel of immunohistochemical anti-bodies have been increasingly applied for the differential diagnosis of these two tumors. MOC-31 has been recently used as specific for adenocarcinomas while reacting with a minimal number of benign and malignant mesothelial proliferations, and HBME-1 has also been presented as a mesothelial cell marker. In this study, we aimed to show the importance of these two antibodies among the environmental MM cases from Southeastern Turkey. Fifty five cases of MM and twenty adenocarcinomas were included in this study. Histochemical (PAS, PAS-D, mucicarmine) and immunohistochemical (Keratin, EMA,CEA, MOC-31, HBME-1) stains have been performed on each case. Keratin was positive in all cases. EMA stained 50 of 55 MM and all the adenocarcinoma cases. According to our results, dPAS, mucicarmen, CEA and MOC-31 positivity was statistically significant in the diagnosis of adenocarcinoma whereas HBME-1 was demonstrable in most MM cases (52/55) and 11 adenocarcinoma cases. This study confirmed that in the diagnostic distinction between MM and adenocarcinoma, immuno-histochemistry is an important diagnostic tool, however, a panel of antibodies must be used rather than any single antibody. HBME-1 should be included in this panel; MOC-31 can be used where CEA is not available or to doublecheck the reactivity of this antibody.